Age is a strong and independent risk factor for dying from breast cancer (BC) in and of itself. This becomes highly significant when considering that BC is the most commonly diagnosed cancer in women and the second most deadly. Hormone positive BC is especially common among older women. While adjuvant hormonal treatment is proven to dramatically reduce the risk of cancer recurrence and mortality for hormone- sensitive BC, evidence shows that about half of all women 65 years discontinue this life-saving treatment. What contributes to discontinuation is poorly understood. Aromatase inhibitors (AIs) are associated with adverse side effects such as an arthralgia syndrome, hot flashes, loss of bone density, and cardiovascular events which may influence whether women persist with the treatment. Although the numbers of older women with BC is growing and this population has disproportionately high mortality rates compared with younger women, little or no research has explored the processes by which women 65 years decide to continue or discontinue AI treatment. Our multidisciplinary study will elicit in-depth narratives to explore what influences te trajectory of continuing or discontinuing an AI in the context of the lives of women 65 years and above. We will gain understanding of how women 65 years interpret, and act upon information that they have received about AIs. In addition, based on the pragmatic evidence in the women's own words, we will develop a novel descriptive framework of the decisional processes about using AIs within the context of the women's lives. The choice of research method is constructivist grounded theory, providing a methodology to access and understand meanings and decisional processes from a personal perspective. Approximately 50 personal interviews with 40 women, 65 years who were treated for primary, invasive loco-regional BC and are either taking an AI or have discontinued the treatment will supply the data. A focused interview guide has been developed from preliminary findings including the PI's research with women 70 years who recently completed treatment for early stage BC. The interview guide will extend previous research to include questions about preferred ways to receive information about AIs and what the women did to self-manage the modifiable factors of side effects. Furthermore, from the perspective of cancer survivorship science, the interview guide contains questions about the role of family and support people. A novel framework will result from this study to provide the foundation to design and test an age- appropriate and cost-effective supportive intervention to improve informed decision making and increase continuation with AIs. We also foresee that the findings may be transferable to women 65 years in other contexts of geriatric oncology and other areas of oncology such as the use of an AI to reduce the relative risk of a first time invasive BC in healthy postmenopausal women.